Here is the tuft testing final setup at the moment. Tufts at the side of the kammback are little bit turbulent with this last roof angle.
Also tried again if I could reach better figures but no luck. Smooth hubcaps were not in place in the last test so that might effect the result. Also I had talk to my phone so that effected a lot to the rest of the tank. First half I was able to rech 2.3 l/100km with boardcomputer. On the way back the same figure was 2.5...